The invention relates to a circuitry for cyclically driving several loads, comprising a basic circuit including an oscillator and successively generating pulses at several outputs, the oscillator comprising a frequency-determining component.
Circuits by which loads in the form of LEDs are cyclically driven are known. Such circuits are used in displays or ornaments, for example. The LEDs are driven by a basic circuit which, for example, is configured as an integrated circuit. The basic circuit comprises several outputs to which different LEDs are connected. In operation, the basic circuit cyclically generates pulses at the outputs so that the LEDs connected to different outputs light up. The repetition rate at which the LEDs are activated depends on the value of a frequency-determining component which is externally connected to the integrated circuit. Usually, this component is a resistor. If the resistance value is high, the repetition rate is low; and if the resistance value is low, the repetition rate of the pulses is high. With this kind of drive, all LEDs are driven by pulses of the same duration. When the LEDs have different colors, this results in different luminosities because the effectiveness of, e.g., a blue LED is lower than that of a red LED. Therefore, the blue LEDs glow less intensely than the red LEDs.